(a) Field of the Invention
The present invention relates to a spray head for a spray paint gun, and more particularly, to one that is adaptable to a shorter and less sophisticate nozzle, thus can be equipped with more derived interchangeable nozzles.
(b) Description of the Prior Art
To ensure stabilized and well distributed air flow, a buffer structure is usually provided between the air outlet at the tip of the spray head and the nozzle and air outlet of the nozzle to any comparatively precision spray paint gun. As illustrated in FIGS. 3, 4 and 5 of the accompanying drawings, a spray head structure of the prior art to lead out consistent air flow to evenly deliver the coating is essentially comprised of an airtight diverting ring (B), a threaded coupler (C), a nozzle (D), a spray head (E) and a nut (F) connected in sequence to the body of the spray gun (A). Wherein, a passage to direct and deliver the coating is formed at the center of the front of the spray gun (A). A screw hole (A1) is formed at the front of the passage and a regulation shaft (G) extends out of the passage. The screw hole (A1) engaged to threaded coupler (C). Two segmental recesses (A2, A3) and a hole (A4) are provided on the surface of outer ring of the screw hole (A1). Two air ducts (A5, A6) are respectively provided in the recesses (A2, A3). Two air ports (B1, B2) and a stub (B3) to match said recesses (A2, A3) and said hole (A4) facing the front end of the spray gun (A) are provided in the diverting ring (B). Two slots (B4, B5) are respectively provided in each of said two air ports (B1, B2).
The diverting ring (B) is abutted to the front end of the spray gun (A) by having inserting the stub (B3) into the hole (A4), wherein, said two air ports (B1, B2) are merely adhered to said recesses (A2, A3) to define two air diverting ports for the air flow passing through said slots (B4, B5). A hollow worm gear (C1) is formed in the rear of the threaded coupler (C) to receive insertion by the diverting ring (B) so that the rear of the threaded coupler (C) is adhered to the diverting ring (B) and engaged to the screw hole (A1) in the front of the spray gun (A). An inner and an outer recesses (C2, C3) are respectively formed in the rear surface of the threaded coupler (C). Plural ventilation pores (C4) provided in the inner recess (C2) are connected through a tapered circular slot (C6) in the front of the threaded coupler (C); and plural ventilation pores (C5), directly connected through the front end of the threaded coupler (C). An inner screw hole (C7) formed in the front center of the worm gear (C1) is engaged to another worm gear (D1) formed in the rear of the nozzle (D). A circular channel (D2) is formed around the worm gear (D1) and plural through holes (D3) are provided in the channel (D2) to connect to the front end of the nozzle (D). Those through holes (D3) are arranged surrounding a nose (D4). The spray head (E) is engaged to the nut (F) and is secured to the front of the spray gun (A) and coupled by the front of the nozzle (D) by means of the outer threads (C8) on the threaded coupler (C) that the nut (F) is engaged to the threaded coupler (C). A concave (E1) and a circular indention (E2) inside the nozzle (E) define a graded space. Air ducts (E3) provided on the concave (E1) communicate two air outlet bases (E4) in symmetric provided externally to the spray head (E). A spray hole (E5) is provided in the center of the circular indention (E2) to allow the insertion by a play of the nose (D4) of the nozzle (D). Disturbance holes (E6) are provided surrounding the spray hole (E5) and a tapered surface (D5) formed to the front by having the circular indention (E2) to hold against the front of the nozzle (D).
In practice, high pressure air fed to the spray head comprised of those members as described above passes through those two segmental recesses (A2, A3) in the front surface of the body of the spray gun (A), leaves from those two air ducts (A5, A6), and enters into said two air ports abutted to the diverting ring (B). Wherein, the high pressure air is buffered for the first time and diverted respectively through said two slots (B4, B5) respectively in the inner and out rings of the diverting ring (B) to the inner and outer recesses of the threaded coupler (C) adhered to the rear of the diverting ring (B) [air flow routes respectively illustrated in FIGS. 4 and 5]. The high pressure air is buffered therein for the second time. The high pressure air from the inner recess (C2) flows through those ventilation pores (C4) to those air ports defined by a tapered circular slot (C6) in the front of the threaded coupler (C) adhered to the circular channel (D2) of the worm gear (D1), then the through holes (D3) to the front end of the nozzle (D), and finally into the indention (E2) of the spray head (E). On the other hand, the air flow in the outer recess (C3) passes through the air outlet (C5) to the front end and into the peripheral concave (E1) to the spray head (E). The air in the circular indention (E2) is jetted from those disturbance holes (E6) and the play formed by the insertion of the nozzle nose (D4) into the spray hole (E5) while the air in the concave is (E1) is delivered by those air outlet bases (E4) provided externally to the air ducts (E3) so to disturb both the air flow and the coating jetted from the nozzle (D) for delivering atomized, evenly distributed wide coverage of coating.
However, in the spray head structure of the prior art, the nozzle (D) used relates to a longer body in terms of the configuration of the entire assembly. The matching spray head (E) is also required to have deeper indention (E2) and longer body sufficient to accommodate the insertion of the fully length of the tapered surface (D5) to hold against the circumference of the indention (E2), thus to define the final air port for air jet. As the nozzle is made of stainless steel material and drill work is required for the circular channel (D2) in the rear of the nozzle (D) to connect all way to those multiple through holes (D3) in very small diameter, and the nozzle (D) is comparatively longer, it requires longer and deeper drilling. It makes the drilling difficult to process resulting in frequent drilling error, thus higher percentage of defective products, and increased production cost. Furthermore, the circular channel (D2), those through holes and extended tapered surface of the nozzle (D) not only requires a complicate structure and larger size for the nozzle (D), but also restricts the possibility of interchangeability among different types of the nozzle (D).
The primary purpose of the present invention is to provide an improved structure for a head of a spray paint gun with air pressure stabilizing effects that is adaptable to a shorter and less complicate nozzle, thus to more types of derived nozzles. To achieve the purpose, a threaded coupler is engaged to the air outlet end section of the spray head and a gasket is inserted between the end plane and the threaded coupler. Inner and outer recesses are formed on both abutted surfaces of the end plane and the threaded coupler. Multiple slots arranged in proper distance among one another are formed in the gasket corresponding to those inner and outer recesses. One air outlet duct is each provided in those inner and outer recesses in the spray gun. Air outlets provided in the outer recess of the threaded coupler is connected to a ditch segregated by a flange. Another ditch is formed in the front of the threaded coupler relatively to a hollow worm gear and a push-pull plane is formed to the outer wall of the ditch. Air ventilation holes in the inner recess are drilled all way to the ditch. The nozzle is engaged to an inner screw hole at the front end of the hollow worm gear in the threaded coupler. A circular segment extends from the outer circumference of the nozzle into an inner edge of its corresponding circular ditch. A push-pull surface is formed surrounding the edge of the circular indention in the nozzle to accommodate insertion of the nozzle for the push-pull surface is abutted to the push-pull plane in the circular ditch of the threaded coupler. As a result, all the ports in the air flow passage are provided in the threaded coupler to provide a shorter structure for the nozzle.